Captura, transporte y almacenamiento de CO2 Captura de CO2 por postcombustin
Master en Ingeniera Ambiental Curso 2012-2013
Prof. Vicente J. Corts
Indice
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Presentation Outline
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Technology options
CO23-15%
CO240%
CO2>95%
Adapted from EPRI 2007
Capture Routes: Classification
Post-combustion capture: separation CO2-N2 Pre-combustion capture: separation CO2-H2 Oxyfuel combustion (Denitrogenation): pre-separation O2-N2
Post-comb. (flue gas) p (bar) [CO2] (%) ~1 bar 3-15% Pre-comb. (shifted syngas) 10-80 20-40% Oxyfuel comb. (exhaust) ~1 bar 75-95%
Partial pressure of CO2 in the flue gases from existing power plants is very low
The challenge: huge scale of operation 500 MW USC Coal Fired Power Station
Coal feed : 164 x 103 kg/h Stack gas flow rate : 2.200 x103 kg/h ~ 54 x103 t/d CO2 flow rate : 370.000 kg/h ~ 8,9 x103 t/d Nr. of tank trucks with trailers* : 300/d, one in five minutes
Figures for a 500 MW SC Coal Fired Power Station: 12% higher
*Cryogenic conditions typically 1,7 MPa, -30oC
Presentation Outline
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Postcombustion: basic approach
NGas Air Coal CO24-5% N2 O2 CO2 Separation CO2
0.35g CO2/kWh
Power & Heat CO210-14% 0.9 g CO2/kWh
Compatible with low partial pressure of CO2 in flue gases Suitable for retrofittings and capture-ready concepts Leading candidate for gas-fired power plants, if required
CO2 Dehydration and Compression
Learning by doing through easily scalable pilots processing slip streams Solvent technologies proven on a smaller scale at CPI* Learning by searching will lead to better solvents and process integration Applicable to other carbon-intensive industries: oil refining, cement
*chemical process industries
Technology options for postcombustion CO2 capture
CO2 Separation and Capture
Absorption Adsorption Cryogenics Membranes Microbial/Algal Systems
Chemical
Amines1 Ammonia Other2
Adsorber Beds
Alumina Zeolite, MOFs Activated carbon
Gas Separation
Polyphenylenoxide Polyimides
Physical
Selexol Rectisol Other
Regeneration Methods
Pressure Swing Temperature Swing Washing
Gas Absorption
Polypropylene
1. Primary, secondary, tertiary, sterically hindered 2. Alkaline compounds, Salts of aminoacids
Ceramic Based Systems
Presentation Outline
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Absorption schematics Uptake of CO2 into de bulk phase of a liquid solution w/o chemical reaction
ABSORBER
VENT GAS TO STACK LEAN SOLVENT
STRIPPING
CO2 TO COMPRESSOR SOLVENT
CO2 CAPTURE
RICH SOLVENT (+ CO2) FLUE GAS (CO2)
SOLVENT REGENERATION
MAKE-UP ENTALPHY
SPENT SOLVENT
Flue gas contacted with a reagentcontaining solvent CO2 transfers from the gas phase into the liquid phase CO2 selectively reacts with the reagent
The CO2-loaded rich solution is pumped to a regenerator vessel to be heated Gaseous CO2 is stripped (liberated) Lean solution is circulated back to the absorber
Chemical vs. Physical Absorption
IEA GHG
Simplified flowsheet
Source: SINTEF, 2010
Simplified flowsheet
Types of columns
Counter current flow through a packed column is most common
Plate towers are also used, mainly in the stripping step*
*Image
source: Mass Transfer Operations, R.E. Treybal, (1980) McGraw-Hill
Absorption technology issues
1. Very high gas flow rates: large columns 2. Large solvent flow rates: important auxiliaries consumption 3. Steam extraction for solvent regeneration: parasitic load of 20-30% * 4. Capture chemistry contaminated by SO2/SO3: concentrations < 10 ppmv required 5. Solvent and reaction products may exit the absorber: potential impact on HS&E of nitramines and nitrosamines
* CO2 compression included
GCCSI
Near-term absorption technologies
1. Currently emphasis on absorption on near-term technologies 2. Industrys CO2 capture chemistry knowledge and overall process experience are both heavily slated towards absorption 3. All near-term technologies are solvent based involving either proprietary amines or ammonia 4. Distinction between these technologies are Specific capture chemistry Process configuration and integration into the power plant 5. Near-term technologies have been tested at scales on slip streams no larger than 5-25 MWe from coal-fired power plants
GCCSI
Commercially available solvent systems
IEA GHG
Absorption solvents Key characteristics
High reactivity with respect to CO2 To reduce height requirements for the absorber and/or Reduce solvent circulation flow rates
Low regeneration cost
Based on a low heat of reaction with CO2
High absorption capacity
Which directly influences solvent circulation flow rate requirements
Davidson
Absorption solvents Key characteristics
High thermal stability Reduced solvent waste due to thermal degradation
Reduced solvent degradation
Reduced solvent waste due to chemical degradation
Low solvent costs
Easy and cheap to produce
Low environmental impact
Davidson
Amine-based absorption processs Primary and Secondary Amines
Low T
2(R-NH2) + CO2
R-NH-COO- + R-NH3+
Carbamate
Two solvent molecules required for each CO2 molecule sorbed Fast rate, low capacity Example: Mono-ethanol amine, MEA
HOCH2CH2NH2
Amine-based absorption processs Tertiary and Hindered Amines
R3-N + CO2 +H2O
R3-NH + HCO3Bicarbonate
One solvent molecule required for each CO2 molecule sorbed Slow rate, promoters required, high capacity Example: MDEA (HOCH2CH2)2NCH2
Block flow diagram of the Econamine FG+ process using MEA
Ammonia-based absorption process Chilled ammonia
cooled flue gas
Ammonium carbonate solution + CO2
Ammonium bicarbonate
T raise at relatively high P
CO2 (g) (NH4)2CO3 (aq) + CO2(aq) +H2O(l) (NH4)2CO3 (aq)
CO2 (g) 2(NH4)HCO3 (aq) (NH4)2CO3 (s)
A slurry consisting of a liquid in equilibrium with solid ammonium bicarbonate (NH4HCO3) is produced in an absorber The slurry releases CO2 at a relatively high pressure after being heated in a desorber
Ammonia-based absorption process
Solvents for Post Combustion Chilled ammonia advantages High CO2 purity Tolerant to oxygen and flue gas impurities Stable reagent, no degradation No emission of trace contaminants Low cost, globally available reagent
Simplified flow sheet ACAP process
Other absorption processses Potasium carbonate
CO32- + CO2 + H2O 2 HCO3-
Amino Acid Salts
-OOC-R-NRH
+ CO2 + H2O
OOC-R-NRH2+ HCO3-
Non-volatile Non toxic and biodegradable Resistant to degradation by O2, SOX and NOX Slower kinetics which gives greater tower height Kinetics improved through the use of promoters
Solvents for Post Combustion Comparison of Solvent Properties
Cost (US$/lb) MEA MDEA Ammonia Potassium Carbonate 40 300 5 40
Volatility
(atm x 103 at 40C)
Degradation High Moderate None None
Corrosion High Moderate High High
0.1 0.003 200 0
Rochelle, 2007
Absorption technology: energy penalty Sankey diagram : Postcombustion USC pulverized coal PP
NET OUTPUT 34,2% FUEL 100%
CO2COMPRESSION 3,4% CAPTURE PROCESS (Enthalpy&Electricity) 5,7% AUXILIARIES 3,4%
REFERENCE PLANT USC PC
COOLING 53,0%
WITH CCS
10 20 30 40 EFFICIENCY, %
50
Based on MIT data
Absorption technology: energy penalty
50 45
Subcritical power plant
50 45 40
43.3
USC power plant
Efficiency, % Efficiency
Efficiency, % Efficiency
40
34.3
Amine unit (entalphy)
-5.0
CO2 Compressor -3.5 Amine unit (power) -0.7
35
35
Amine unit (entalphy)
34.1
-5.0
30
CO2 Compressor -3.5 Amine unit (power) -0.7
30
USC no Capture USC with Capture
25.1 With Capture
25 20
No Capture
25 20
Subcritical
Ultrasupercritical
Carbon capture quotients
CCQ: relative increase or decrease in the emission factor of a substance due to a certain capture technology
CCQ x, y, z =
EF CCS x, y, z EF noCCS x, y
CCQx,y,z < 1 indicates a decrease in emission factor as a consequence of CCS
CCQx
50
CCQx,y,z EF CCSx,y,z EF noCCSx,y
Carbon capture quotient for air pollution substance 'x', given energy conversion technology 'y' and CO2 capture technology 'z Emission factor reported/estimated for air pollution substance 'x', energy conversion technology 'y' and CO2 capture technology 'z Emission factor for air pollution substance 'x' and energy conversion technology 'y' reported/estimated for the reference plant without CO2 capture
EEA, 2011
Air pollution impacts
Capture quotients for primary energy, CO2, SO2, NOX, PM and NH3 Postcombustion results in no NOX reduction and much higher emission of other nitrogen compounds
Capture Technology
Conversion technology
Primary energy CCQCO2 new capture
CCQSO2
CCQNOX
CCQPM
CCQNH3
NGCC Post-combustion PC Precombustion IGCC NGCC Oxyfuel combustion PC
1.11 1.22 1.13 1.20 1.22
0.13 0.10 0.11 0.02 0.05
0.15 0.45 0.06
1.00 0.94 0.85 0 0.42
0.71 1.00 0.06
1.25-30.30 17.50-45.25 -
EEA, 2011
Presentation Outline
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Adsorption schematics Uptake of CO2 onto the surface of a solid sorbent via physisorption or chemisorption in packed or fluidized beds
ADSORPTION
VENT GAS TO STACK LEAN SORBENT
DESORPTION
CO2 TO COMPRESSOR SORBENT SORBENT SORBENT REGENERATION REGENERATION MAKE-UP ENTALPHY
CO2 CAPTURE
P RICH SORBENT (+ CO2)
FLUE GAS (CO2)
SPENT SORBENT
Physisorption vs. Chemisorption
Van der Waals: Weak forces
Covalent bonding: Strong forces, sites necessary
Adsorption beds Packed beds
Flue gas flows through void spaces between adsorbent particles Regeneration by heating the CO2 -laden adsorbent Flue gas diverted to a second packed bed At least two beds are needed
GCCSI
Adsorption beds Fluidized beds
Flue gas flows upward through a column Adsorbent particles are suspended in the gas flow Sorbent circulated between absorber and regenerator At least two vessels are needed
GCCSI
Adsorbents characteristics
Solid (usually granular, beads, pellets) material Selective for one or more components in the gas phase High accesible porosity Large internal surface area (up to 1000-3000 m2/g)
Micropores dp< 20 nm
CO2 collision diameter 3.996 nm
Mesopores 20 nm dp < 500 nm Macropores dp 500 nm
Pore size distributions of common clases of adsorbents
Adsorbent attributes
Capacity: the amount of adsorbate taken up by the adsorbent per unit mass ( or volume) of the adsorbent Selectivity: is the ratio of the capacity of one component to that of another at a given fluid concentration Regenerability: Necessary to have the the adsorbent operating in sequential cycles Related to the strenght of adsorption forces Affects the fraction of the original capacity that is retained : working capacity Mass transfer kinetics: fast diffusion of adsorbate required Mechanically strong to withstand bulk handling and attrition
Working capacity of adsorbents The Achilles Heel of Adsorption processes
Working capacity 1.3%wt 0.3 mole/kg adsorbent 500 MWe Supercritical PS. 160 kmol CO2/min Adsorbent circulation rate 530 t/min
Rotary Wheel contactor Wheel : diameter 10m, depth 1m 1 minute regeneration time 8 wheels in parallel
Adsorbents Molecular sieves: Zeolites
A cage-like structure which admits only molecules less than a certain size e.g. 13X (pore diameter 7) will admit He, H2, H2O, CO, CO2, N2 For CO2, there is also significant chemisorption to the surface, which gives the required selectivity over other gases
Cations ( e.g. Na+)
Type X or Y Zeolite
Adsorbents Metal Organic Frameworks (MOFs)
Metal Oxide clusters connected by organic linkers MOF-177 soaks up 140% of its weight in CO2 at room temperature and reasonable pressure (32 bar)
Li, J.R Coordination Chemistry Reviews 255 (2011) 17911823
Regeneration Options
PSA : pressure swing adsorption
Pressure is varied : high absorption, low desorption Rapid cycle easily achieved Short cycle times possible: seconds
TSA : temperature swing adsorption
T is varied : low absorption, highdesorption Rapid cycle requires very fast heat transfer: difficult to achieve Minimum cycle time: minutes
Others
VSA , vacuum swing adsorption:pressure is varied from a vacuum to value above Patm ESA, electrical swing adsorption: a current is applied cyclically to a conducting adsorbent such as a carbon
Adsorption technology issues
Regeneration energy should be lower relative to solvents but effects such as Heat capacity Working capacity Heats of reaction needs consideration Potential disadvantages: Particle attrition Handling of large volumes of sorbent Thermal management of large-scale adsorber vessels Adsorption processes are still in the kW range of demonstration Current development of new materials such as metal organic frameworks (MOFs), zeolites and zeolitic imidazolate frameworks (ZIFs) shows promising
GCCSI
Indice
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Membrane technology schematics Separation of CO2 from flue gas by selectively permeating it through the membrane material
High permeability
VENT GAS CO2
High selectivity
FLUE GAS GAS (CO2)
POLYMER, METALLIC OR CERAMIC MEMBRANE
CO2 permeation requires CO2 partial pressure gradient across the membrane Option 1: pressurizing the flue gas on one side of the membrane Option 2: applying a vacuum on the other side of the membrane Option 3: both
Membrane technology issues
Claimed to potentially offer low energy capture processes Small foot print for the capture system Modular design that may allow for flexible operation Testing conducted at scales less than 1 t/day. No public results available Potential fouling of the membrane surfaces from particulate matter Uncertainty about performance and cost of large-scale efficient vacuum pumps and compressors Ability to integrate the process into a power plant
GCCSI
Types of membranes for CO2 removal
1. First Generation: Cellulose acetate (Cynara, UOP, Grace) Polysulfone (Air Products Prism) Generally spiral wound ~ 3,000 m2 per m3 volume 2. Second Generation: Polyimides (Ube, MEDAL) Most likely hollow fibers ~ 10,000 m2 per m3 volume Alternatively spiral wound modules 3. Non selective membranes: gas liquid-contactors Liquid solvent on one side Gas stream on the other side
Membrane Technology Spiral Wound Module
~ 3000 m2 per m3 volume
Source: CO2CRC, 2009
Membrane Technology Hollow Fibre Modules
Fibre 0.1-0.5 mm Skin layer ~0.1 m thick
~ 10,000 m2 per m3 volume
Source: CO2CRC, 2009
Membrane Technology Gas-Liquid contactor Liquid solvent on one side of the membrane and the gas stream on the other side of the membrane
Membrane is not selective; only separates gas and liquid phases Diffusion through porous followed by chemical absorption in liquid Size of the pores: Large enough so that the CO2 can easily pass through the membrane Small enough so that the liquid will not wet the pores
Flue Gas Microporous Membrane Absorption Liquid
CO2
CO2
Membrane Technology Gas-Liquid contactor
Source: CO2CRC, 2009
Indice
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
State of postcombustion development
Absorption
Commercial Usage in CPI* Operational Confidence Primary Source of Energy Penalty Development Trends High High Solvent regeneration (thermal) New chemistry, thermal integration
Adsorption
Moderate High, but complex Sorbent regeneration (thermal/vacuum) New chemistry, process configuration
Membrane
Low/Niche Low to moderate Compression on feed and/or vacuum on permeate New membrane, process configuration
* Chemical Process Industries
GCCSI
Indice
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
Major challenges for postcombustion
1. Reduction of the large parasitic load imposed on a power plant Mostly derived from the energy needed to regenerate the solvent Energy required for compression is less than that required for capture 2. Development of new chemistry, new process designs, and novel power plant integration schemes All aimed at reducing the energy penalty 3. Capital cost reductions, solvent degradation, solvent volatility, and other Secondary to the prime issue of reduction in parasitic load 4. Identification of amine derivatives and degradation products effects on HS&E Countermeasures to be developed
GCCSI
Indice
Alternativas tecnolgicas para la captura de CO2 Fundamentos Absorcin Adsorcin Membranas Estado de desarrollo Principales retos Proyectos europeos de demostracin
European demo projects
Don Valley Pre 180 M
Rotterdam 2 Post 180 M
Belchatow Post 180 M
Janschwalde Oxy-PC 180 M
?
COMPOSTILLA Oxy-CFB 180 M
?
Porto Tolle Post 100 M
European demo projects
European demo projects
Rotterdam Capture: 1.2 MMt CO2/y Storage : depleted gas fields, N.Sea Industrial partners: EON/Electrabel
